feat(medusa): Add /admin/products/:id/variants end point (#1471)

* feat(medusa): Add /admin/products/:id/variants end point

* test(medusa): Fix get-variants test casees

* feat(medusa): Include the config to the ProdutService#retrieveVariants as a method parameter

* feat(medusa): Improve get-variants endpoint

* feat(medusa): Improve get-variants endpoint

* test(medusa): Fix unit tests

* test(medusa): Fix unit tests

* feat(medusa): Improve typings

* feat(medusa): Update according to feedback

* feat(medusa): Update according to feedback

* test(medusa): Fix list-variants tests

* feat(medusa): Getting the variants from the product end point should use the productVariantService

* fix(medusa): list-variants expand possibly undefined

* Fix(medusa): List-variants endpoint

* fix(medusa): Tests suite for list-variant

* test(integration-tests): Fix yarn lock

* test(integration-tests): Fix yarn lock

packages/medusa/src/helpers/test-request.js

@@ -4,6 +4,7 @@ import jwt from "jsonwebtoken"
 import { MockManager } from "medusa-test-utils"
 import "reflect-metadata"
 import supertest from "supertest"
+import querystring from "querystring"
 import apiLoader from "../loaders/api"
 import passportLoader from "../loaders/passport"
 import servicesLoader from "../loaders/services"
@@ -68,10 +69,10 @@ apiLoader({ container, app: testApp, configModule: config })
 const supertestRequest = supertest(testApp)
 
 export async function request(method, url, opts = {}) {
-  let { payload, headers } = opts
+  const { payload, query, headers = {} } = opts
 
-  const req = supertestRequest[method.toLowerCase()](url)
-  headers = headers || {}
+  const queryParams = query && querystring.stringify(query);
+  const req = supertestRequest[method.toLowerCase()](`${url}${queryParams ? "?" + queryParams : ''}`)
   headers.Cookie = headers.Cookie || ""
   if (opts.adminSession) {
     if (opts.adminSession.jwt) {